Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 305 PM EST Sat Jan 27 2018 Valid 00Z Sun Jan 28 2018 - 00Z Tue Jan 30 2018 ...Heavy rain and thunderstorms could lead to flash flooding along the central Gulf coast through tonight... ...Heavy snow through tonight over the northern Cascades into the northern Rockies... ...Watching for the potential of a storm development off the East Coast on Monday... The upper-level pattern is forecast to become more amplified across the U.S. during the next few days. This will favor arctic air from Canada to surge into the eastern U.S. while warmer air is expected to overspread the western U.S. First of all, a coastal front with a weak surface low pressure center near the central Gulf coast has been associated with clusters of heavy showers and thunderstorms. This system is forecast to move generally east-northeastward across the Florida Peninsula into the Southeast through the rest of the weekend, bringing a threat of flash flooding along the central Gulf coast tonight. By Monday, it should continue to move off the southeast U.S. coast and should begin to merge with a cold front arriving from the Mid-Atlantic. Computer models still show noticeable disagreement on how far off the East Coast the storm will intensify on Monday. Nevertheless, a couple of inches of rain is forecast near the Mid-Atlantic coast through Monday. Farther inland, as arctic air continues to filter in from Canada, some light snow and snow showers are expected to spread from the Midwest into the Appalachians on Monday near a weakening arctic cold front. Temperatures will start out very mild for the rest of the weekend across much of the eastern U.S. ahead of the arctic front as much colder air filters into the northern Plains, reaching the East Coast later on Monday. Over the western U.S., snow will be heavy through tonight across the northern Cascades into the northern Rockies as moisture from a low pressure system currently moving onshore across the Pacific Northwest interacts with a stationary arctic front along the east slopes of the northern Rockies. Precipitation should become less intense on Sunday as an upper-level ridge begins to build northward into the region. By Monday, another cold front is forecast to move into the Pacific Northwest will a renewed around of precipitation. Temperatures will become progressively milder across much of the rest of the western U.S. with fine and dry conditions as the upper-level ridge continues to build and becomes the dominant feature. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php